Arginase-1 is a Novel Immunohistochemical Marker of Hepatocellular DifferentiationOrdóñez, Nelson G. MDAdvances in Anatomic Pathology: July 2014 - Volume 21 - Issue 4 - p 285–290 doi: 10.1097/PAP.0000000000000022 New Antibody/Techniques Abstract Author Information Arginase-1 is an enzyme that catalyzes the hydrolysis of arginine to ornithine and urea in the urea cycle. In normal tissues, arginase-1 is primarily expressed in hepatocytes. Recent investigations have reported that the vast majority of hepatocellular carcinomas express this marker, but it is found only rarely in nonhepatocellular tumors. Owing to its restricted expression in hepatocellular carcinomas, arginase-1 has proved to be a useful immunohistochemical marker for assisting in distinguishing between these tumors and other neoplasms with which they may be confused. Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX The author has no funding or conflicts of interest to disclose. Reprints: Nelson G. Ordóñez, MD, Department of Pathology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (e-mail: firstname.lastname@example.org). © 2014 by Lippincott Williams & Wilkins.